Supplementary Material

Expression of obscurin A during zebrafish development. (A-C) RT-PCR
expression of obscurin A (A,B) and -actin (C) at 3 (lane 2), 4.5 (lane 3), 6 (lane 4), 8.5 (lane 5),
10 (lane 6), 11.5 (lane 7), 13 (lane 8), 15 (lane 9), 24 (lane 10), 33 (lane 11), and 72 (lane 12) hpf
time points. Both obscurin A primers demonstrate expression of obscurin by the time the first
somites start to form (lane 6: 10 hpf). [Lane 13 represents a control with RT but no RNA; Lane 14
represents a control with RNA but no RT). (D) Immunostaining for obscurin A in a 20 hpf embryos
demonstrates localization at the newly forming somite boundary (arrowhead). (E) In a 20 hpf
embryo, RNA in situ hybridization using an obscurin A riboprobe demonstrates localization
(arrowhead) of the obscurin mRNA to the somite boundary early in boundary formation.